Consolidate ifdef sections.

Makes code shorter, easier to read.
Adding documentation.
For consistency, make functions which read data from the Exodus file
follow 2 conventions:
.) Be called read_xyz()
.) Return void

Also check Exodus error codes in all relevant functions.
Misc simplifications, improvements:

* Removed last remaining inline member function.
* Always check Exodus return codes.
* Get rid of unnecessary req_info member variable.
* Use the inquire() function instead of calling ex_inquire() directly.
* Removing the ret_int, ret_char, and ret_float class member variables.
* Removing ex_version as a class member.
* Removing comp_ws and io_ws as class members.
* Remove debugging functions apparently not used for anything.
* Use a vector of ints rather than a dodgy cast!
* Title is never empty.
* Initialize all relevant member vars.
Merge branch 'exII_refactor'